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Ah Mensa.
I was a member back in my undergraduate days.
We were really organized and even managed to get enough people to start an official Mensa club at the university. Thats harder than it sounds when the admissions test excludes 98% of the population. I was the treasurer which in reality meant I managed the pizza money and picked up the pizza for the monthly meetings which were interesting.
I still remember my feelings of smugness when I got in. I was a shallower person back then and felt IQ to be much more important than I do now. Not sure how its done today but back then the official test was a timed paper and pencil exam with a proctor and you got the results via mail a while later.
Good memories overall but I let my membership expire after I graduated. I understand the appeal but am no longer a fan of its exclusionary nature centered as it is around an inherent biological variance.
What we do with the gifts we are given is much more important than the exact abundance and quantity of what we are born with. With the benefit of age I am now much more interested in groups that focus on the former not the latter.